# Key Structs Definition - all structs used are defined in the [Fermi-v1 Repo](https://github.com/Fermi-DEX/Fermi-Pro). We utilize **zero-copy** for memory efficient storage of large data structures.
## Market State ```rust pub struct Market { /// PDA bump pub bump: u8, /// Number of decimals used for the base token. /// /// Used to convert the oracle's price into a native/native price. pub base_decimals: u8, pub quote_decimals: u8, pub padding1: [u8; 5], // Pda for signing vault txs pub market_authority: Pubkey, /// No expiry = 0. Market will expire and no trading allowed after time_expiry pub time_expiry: i64, /// Admin who can collect fees from the market pub collect_fee_admin: Pubkey, /// Admin who must sign off on all order creations pub open_orders_admin: NonZeroPubkeyOption, /// Admin who must sign off on all event consumptions pub consume_events_admin: NonZeroPubkeyOption, /// Admin who can set market expired, prune orders and close the market pub close_market_admin: NonZeroPubkeyOption, /// Name. Trailing zero bytes are ignored. pub name: [u8; 16], /// Address of the BookSide account for bids pub bids: Pubkey, /// Address of the BookSide account for asks pub asks: Pubkey, /// Address of the EventHeap account pub event_heap: Pubkey, /// Oracles account address pub oracle_a: NonZeroPubkeyOption, pub oracle_b: NonZeroPubkeyOption, /// Oracle configuration pub oracle_config: OracleConfig, /// Number of quote native in a quote lot. Must be a power of 10. /// /// Primarily useful for increasing the tick size on the market: A lot price /// of 1 becomes a native price of quote_lot_size/base_lot_size becomes a /// ui price of quote_lot_size*base_decimals/base_lot_size/quote_decimals. pub quote_lot_size: i64, /// Number of base native in a base lot. Must be a power of 10. /// /// Example: If base decimals for the underlying asset is 6, base lot size /// is 100 and and base position lots is 10_000 then base position native is /// 1_000_000 and base position ui is 1. pub base_lot_size: i64, /// Total number of orders seen pub seq_num: u64, /// Timestamp in seconds that the market was registered at. pub registration_time: i64, /// Fees /// /// Fee (in 10^-6) when matching maker orders. /// maker_fee < 0 it means some of the taker_fees goes to the maker /// maker_fee > 0, it means no taker_fee to the maker, and maker fee goes to the referral pub maker_fee: i64, /// Fee (in 10^-6) for taker orders, always >= 0. pub taker_fee: i64, /// Total fees accrued in native quote pub fees_accrued: u128, /// Total fees settled in native quote pub fees_to_referrers: u128, /// Referrer rebates to be distributed pub referrer_rebates_accrued: u64, /// Fees generated and available to withdraw via sweep_fees pub fees_available: u64, /// Cumulative maker volume (same as taker volume) in quote native units pub maker_volume: u128, /// Cumulative taker volume in quote native units due to place take orders pub taker_volume_wo_oo: u128, pub base_mint: Pubkey, pub quote_mint: Pubkey, pub market_base_vault: Pubkey, pub base_deposit_total: u64, pub market_quote_vault: Pubkey, pub quote_deposit_total: u64, pub reserved: [u8; 128], } ``` ## Orderbook State We utilise a custom Binary Tree data structure to store the orderbook state, for efficient insertion and retrieval of the best quote on a particular bookside. ```rust pub struct Orderbook<'a> { pub bids: RefMut<'a, BookSide>, pub asks: RefMut<'a, BookSide>, } ``` ```rust #[account(zero_copy)] pub struct BookSide { pub roots: [OrderTreeRoot; 2], pub reserved_roots: [OrderTreeRoot; 4], pub reserved: [u8; 256], pub nodes: OrderTreeNodes, ``` 
pub struct OrderTreeNodes {
    pub order_tree_type: u8, // OrderTreeType, but that's not POD
    pub padding: [u8; 3],
    pub bump_index: u32,
    pub free_list_len: u32,
    pub free_list_head: NodeHandle,
    pub reserved: [u8; 512],
    pub nodes: [AnyNode; MAX_ORDERTREE_NODE


pub struct OrderTreeIter<'a> {
    order_tree: &'a OrderTreeNodes,
    /// InnerNodes where the right side still needs to be iterated on
    stack: Vec<&'a InnerNode>,
    /// To be returned on `next()`
    next_leaf: Option<(NodeHandle, &'a LeafNode)>,

    /// either 0, 1 to iterate low-to-high, or 1, 0 to iterate high-to-low
    left: usize,
    right: usize,
}
```rust pub struct Order { pub side: Side, /// Max base lots to buy/sell. pub max_base_lots: i64, /// Max quote lots to pay/receive including fees. pub max_quote_lots_including_fees: i64, /// Arbitrary user-controlled order id. pub client_order_id: u64, /// Number of seconds the order shall live, 0 meaning forever pub time_in_force: u16, /// Configure how matches with order of the same owner are handled pub self_trade_behavior: SelfTradeBehavior, /// Order type specific params pub params: OrderParams, } pub struct OrderWithAmounts { pub order_id: Option, pub posted_base_native: u64, pub posted_quote_native: u64, pub total_base_taken_native: u64, pub total_quote_taken_native: u64, pub taker_fees: u64, pub maker_fees: u64, pub referrer_amount: u64, } ``` ```rust #[repr(C)] pub struct LeafNode { /// NodeTag pub tag: u8, /// Index into the owning OpenOrdersAccount's OpenOrders pub owner_slot: u8, /// Time in seconds after `timestamp` at which the order expires. /// A value of 0 means no expiry. pub time_in_force: u16, pub padding: [u8; 4], /// The binary tree key, see new_node_key() pub key: u128, /// Address of the owning OpenOrdersAccount pub owner: Pubkey, /// Number of base lots to buy or sell, always >=1 pub quantity: i64, /// The time the order was placed pub timestamp: u64, /// If the effective price of an oracle pegged order exceeds this limit, /// it will be considered invalid and may be removed. /// /// Only applicable in the oracle_pegged OrderTree pub peg_limit: i64, /// User defined id for this order, used in FillEvents pub client_order_id: u64, } ``` ## Openorders State ```rust #[account(zero_copy)] #[derive(Debug)] pub struct OpenOrdersAccount { pub owner: Pubkey, pub market: Pubkey, pub name: [u8; 32], // Alternative authority/signer of transactions for a openbook account pub delegate: NonZeroPubkeyOption, pub account_num: u32, pub bump: u8, // Introducing a version as we are adding a new field bids_quote_lots pub version: u8, pub padding: [u8; 2], pub position: Position, pub total_approved_base: u64, pub total_approved_quote: u64, pub open_orders: [OpenOrder; MAX_OPEN_ORDERS], } ``` ## EventHeap ```rust #[account(zero_copy)] pub struct EventHeap { pub header: EventHeapHeader, pub nodes: [EventNode; MAX_NUM_EVENTS as usize], pub reserved: [u8; 64], } ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://fermi-dex.gitbook.io/fermi-dex-docs/technical-overview/technical-overview-v1/key-structs.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.